Sheet feeding apparatus and image forming apparatus

Abstract

A sheet feeding apparatus includes a sheet supporting portion to support a sheet, a feeding member to contact an upper surface of the sheet supported on the sheet supporting portion and feed the sheet, and a drive motor to rotate in a first direction and in a second direction opposite to the first direction. In addition, a lifting mechanism is connected to the drive motor to lift the sheet supporting portion and lower the feeding member in a case where the drive motor rotates in the first direction, and to lower the sheet supporting portion and lift the feeding member in a case where the drive motor rotates in the second direction.

What is claimed is: 
     
       1. A sheet feeding apparatus comprising:
 a sheet supporting portion configured to support a sheet; 
 a feeding member configured to contact an upper surface of the sheet supported on the sheet supporting portion and feed the sheet; 
 a drive motor configured to rotate in a first direction and in a second direction opposite to the first direction; and 
 a lifting mechanism connected to the drive motor and configured to lift the sheet supporting portion and lower the feeding member in a case where the drive motor rotates in the first direction, and to lower the sheet supporting portion and lift the feeding member in a case where the drive motor rotates in the second direction. 
 
     
     
       2. The sheet feeding apparatus according to  claim 1 , further comprising:
 a sheet feed motor configured to drive the feeding member; and 
 a controller configured to control the sheet feed motor and the drive motor, 
 wherein during a job of feeding a sheet from the sheet supporting portion, the controller starts rotation of the drive motor in the second direction after starting feeding a final sheet in the job and before stopping the sheet feed motor. 
 
     
     
       3. The sheet feeding apparatus according to  claim 2 , further comprising
 a conveyance member arranged downstream of the feeding member in a feeding direction of the sheet, and configured to be driven by the sheet feed motor and convey the sheet, 
 wherein the controller is configured to start the rotation of the drive motor in the second direction after a leading edge in the feeding direction of the final sheet in the job has reached the conveyance member and before a trailing edge of the final sheet passes the conveyance member, and thereafter, stop the sheet feed motor after the trailing edge of the final sheet has passed the conveyance member. 
 
     
     
       4. The sheet feeding apparatus according to  claim 3 , further comprising
 a clutch configured to engage and disengage drive transmission from the sheet feed motor to the feeding member, 
 wherein the controller is configured to repetitively execute an operation of engaging the clutch and thereafter disengaging the clutch so that sheets are fed from the sheet supporting portion one sheet at a time, the operation being executed in a state where the feeding member is maintained in contact with an upper surface of an uppermost sheet of the sheets supported on the sheet supporting portion by the drive motor and where driving of the conveyance member by the sheet feed motor is continued. 
 
     
     
       5. The sheet feeding apparatus according to  claim 1 , further comprising:
 a feed position sensor of which a detection signal changes according to whether the feeding member is at a predetermined feeding position; and 
 an urging member configured to urge the feeding member downward, 
 wherein the lifting mechanism is configured to lift and lower the feeding member to an upper position above the feeding position and a lower position below the feeding position, and 
 wherein in a case where the drive motor rotates in the first direction, after the feeding member has moved from the upper position to the lower position, the lifting mechanism allows the feeding member to move from the lower position to the feeding position against an urging force of the urging member by being pressed by the sheet supported on the sheet supporting portion. 
 
     
     
       6. The sheet feeding apparatus according to  claim 1 ,
 wherein the lifting mechanism comprises a swing member supported swingably on a frame member of the sheet feeding apparatus, coupled to the feeding member and configured to swing to lift and lower the feeding member, and 
 wherein the feeding member is removable in a predetermined removing direction with respect to the frame member, and is configured to be disengaged from the swing member along with a removal operation of removing the feeding member in the removing direction and be engaged with the swing member along with an operation of attaching the feeding member in an opposite direction to the removing direction. 
 
     
     
       7. The sheet feeding apparatus according to  claim 1 ,
 wherein the lifting mechanism comprises a first lifting portion configured to lift and lower the sheet supporting portion, a second lifting portion configured to lift and lower the feeding member, and a transmission portion to transmit driving force of the drive motor to the first lifting portion and the second lifting portion, 
 wherein the second lifting portion comprises a swing member supported swingably on a frame member of the sheet feeding apparatus, coupled to the feeding member and configured to swing to lift and lower the feeding member, and a link member supported slidably by the frame member and configured to couple the transmission portion and the swing member, and 
 wherein the link member is configured to convert rotation transmitted from the drive motor via the transmission portion to linear motion along a direction in which the swing member swings, to thereby make the swing member swing. 
 
     
     
       8. The sheet feeding apparatus according to  claim 7 ,
 wherein the swing member is configured to swing about an axis that extends in a width direction of a sheet perpendicular to a feeding direction of the sheet by the feeding member. 
 
     
     
       9. The sheet feeding apparatus according to  claim 7 ,
 wherein the swing member is configured to swing about an axis that extends in a direction parallel to a feeding direction of the sheet by the feeding member when viewed in a vertical direction. 
 
     
     
       10. The sheet feeding apparatus according to  claim 1 ,
 further comprising an urging member configured to urge the feeding member downward, 
 wherein the lifting mechanism comprises a link member configured to move in linkage with lifting and lowering of the feeding member, and a one-way gear configured to mesh with the link member, 
 wherein in a case where the drive motor rotates in the first direction, the link member moves in a movement direction for lowering the feeding member such that the link member follows rotation of the one-way gear by an action of an urging force of the urging member, and 
 wherein in a case where the drive motor rotates in the second direction, the one-way gear becomes a locked state, and the link member is moved in a movement direction for lifting the feeding member by receiving driving force of the drive motor transmitted via the one-way gear. 
 
     
     
       11. The sheet feeding apparatus according to  claim 1 ,
 wherein the lifting mechanism comprises a first lifting portion configured to lift and lower the sheet supporting portion, a second lifting portion configured to lift and lower the feeding member, and a reduction gear train comprising a worm gear and configured to increase a torque from the drive motor and transmit the torque to the first lifting portion and the second lifting portion. 
 
     
     
       12. An image forming apparatus comprising:
 the sheet feeding apparatus according to  claim 1 ; and 
 an image forming unit configured to form an image on a sheet fed from the sheet feeding apparatus.